JP2002112596A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-priced and high-performance controller for a permanent magnet type synchronous motor, which enables high efficiency and highly reliable operation through simplified control. SOLUTION: Two-phase currents Iu, Iv of the permanent magnet type synchronous motor 20 are detected and asynchronization and unstable region of the motor are detected, based on differences Δid, Δiq between actual current values Id, Iq of motor subjected to coordinate converted from two-phase currents having a coordinate conversion means 17 and current values Imd, Imq, calculated from a motor model calculation means 18. Here, if a d-axis current error Δid is such that a<Δid<b (a, b are predetermined values), present conditions are defined as the stable operating conditions. If the d-axis current error does not lie within the prescribed range, the present conditions are defined as unstable operating conditions. Moreover, if Δid<=a, the phase is controlled so as to be delayed, and ifb<=Δid, the phase is controlled so as to lead. In addition, if the present position θ of a rotor (not shown) of the permanent magnet type synchronous motor 20 is corrected, determination as to which is similar to the control as explained above is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for efficiently operating a permanent magnet type synchronous motor by using a semiconductor power converter such as an inverter. The present invention relates to a sensorless vector control type control device that performs proportional control.

[0002]

2. Description of the Related Art In controlling a synchronous motor having a salient polarity such as a permanent magnet type synchronous motor or a reluctance motor, a position detector for detecting the position (polar position) of the rotor is generally required. The current phase of the stator winding is controlled in synchronization with the set position. Here, a Hall element, an encoder, a resolver, or the like is used as a rotor position detector. High-efficiency operation when the position of the rotor can be detected can be relatively easily realized. In the permanent magnet type synchronous motor, the current in the magnetic flux direction generated by the permanent magnet of the rotor, that is, the d-axis current Id is set to zero. = 0 control is generally employed. In the case of a motor having saliency in the rotor, such as a permanent magnet type synchronous motor, the d-axis current does not contribute to the torque, so that Id = 0 control minimizes the copper loss in the stator winding. This is because On the other hand, besides the control method of detecting the magnetic pole position and controlling the current phase of the motor as described above, vector control for controlling the voltage and frequency of the motor simply in proportion is well known. FIG.
Shows a control block diagram of vector control. In FIG. 4, a desired frequency of a permanent magnet type synchronous motor 7 (hereinafter simply referred to as “motor 7”) is set by a frequency setting means 1, and the frequency is changed in a ramp function by an acceleration / deceleration calculation means 2. In the frequency (f) / voltage (V) conversion means 3, a voltage substantially proportional to the frequency is obtained by storage or calculation, and a voltage command V according to the frequency command f 'is obtained.
Is output.

The integrating means 4 integrates f1 ', which is the sum of a frequency command f' output from the acceleration / deceleration calculating means 2 and a correction amount Δf 'described later, and applies a voltage to be applied to the stator winding of the motor 7. Is calculated. The PWM control unit 5 performs pulse width modulation on the basis of the magnitude and the phase θ of the voltage command ν ′, generates a drive pulse, and controls ON / OFF of the switching element of the inverter 6. The inverter 6 outputs a three-phase AC voltage of which pulse width is controlled, and this voltage is applied to the stator winding of the permanent magnet type synchronous motor 7 to generate a rotating magnetic field. Here, in general, the vector control has a problem in stability in that the torque oscillates steadily, and when the load suddenly changes, the motor loses synchronism and becomes inoperable.
Therefore, the input current of the motor 7 is detected, and the three-phase / two-phase conversion, coordinate conversion, filter processing,
By performing a proportional amplification process, a deviation calculation process, and the like, a current component orthogonal or parallel to the applied voltage vector is detected, and the detected current component is fed back to the voltage frequency command f ′ as a correction amount Δf ′, thereby improving control stability. Is increasing.

[0004]

However, a control device provided with a rotor position detector can relatively easily realize high-efficiency operation by controlling Id = 0, but has a drawback in miniaturization of the device. In addition, since multiple wires and receiving circuits for transmitting the signal of the detector are required, reliability, workability,
There is a problem in terms of price, etc. On the other hand, the conventional vector control shown in FIG. 4 does not require a position detector and is simple in control, so that the cost of the control device can be reduced, but the position of the rotor is unknown. , Id = 0 control could not be adopted, and high-efficiency operation was difficult.

Further, in the sensorless vector control, since no position detector is mounted, speed / position information is estimated by a predetermined calculation, so that the motor loses synchronism due to a change in input voltage or a problem of estimation accuracy. The possibilities were great.

Therefore, the present invention is to solve the above-mentioned problems and to provide a low-cost and high-performance permanent magnet type synchronous motor control device which enables highly efficient and reliable operation with simple control. It is.

[0007]

According to a first aspect of the present invention, a power converter converts a voltage applied to a winding of a permanent magnet type synchronous motor to a frequency substantially proportional to a voltage applied to the winding. In the control device for a permanent magnet type synchronous motor that controls the motor by controlling at least two-phase current flowing through the winding, a current component parallel to a voltage vector applied to the motor and a current component A coordinate conversion unit for separating the current into orthogonal current components, and a unit for detecting a step-out and unstable region of the motor from a difference between the detected current and a current calculated from a model of the coordinate conversion unit.

According to the first aspect of the present invention, the control device of the present invention can detect the stability of the current operation state of the electric motor only by calculation.

According to a second aspect of the present invention, a phase of an output voltage is corrected by correcting a current target value based on a difference between currents in which a step-out and an unstable region of the motor are detected. That is.

According to the second aspect of the present invention, the control device of the present invention corrects the phase after detecting step-out,
Correcting the Id current target value enables stable operation of the motor.

According to a third aspect of the present invention, the position of the motor estimated by the rotor position estimating unit is corrected based on the difference between the currents in which the step-out and the unstable region of the motor are detected. That is.

According to the third aspect of the present invention, the control device of the present invention corrects the phase after detecting out-of-step.
Correcting the estimated current position θ enables stable operation of the electric motor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are vector diagrams for explaining the basic principle of the present invention. In a permanent magnet type synchronous motor, the magnetic flux vector Ψm created by the permanent magnet of the rotor is set on the d-axis, and the orthogonal coordinates obtained on the d-axis are dq axes. The obtained orthogonal coordinates are defined as PQ axes. It is also assumed that both coordinate axes maintain the load angle δ and rotate counterclockwise at an angular frequency ω. Assuming that the current vector at this time is i, the current is represented by a P-axis current (active power component) ip and a Q-axis current (reactive power component) iρ when observed on the PQ axis and a dq axis. It is divided into two orthogonal components of the d-axis current id and the q-axis current ip at the time of observation. First, the voltage ν ′ and the current i
Since ρ is orthogonal to ρ, the reactive power Qi output from the inverter can be obtained from the product of the two as shown in Expression 1.

[0014]

(Equation 1) Next, regarding the reactive power as viewed from the motor side, FIG.
This will be described with reference to FIG. The no-load induced voltage em generated by the rotation of the magnetic flux generated by the permanent magnet has a magnitude of ω
ψm is present on the q-axis (ψm is a vector Ψ
m)). Voltage em and current i orthogonal thereto
The product of d, ie, ωψmid, becomes reactive power. The magnitude of the reactance drop eL due to the current i (magnitude I) is calculated by using the inductance L of the stator winding as ωL
I. Since eL and i are in an orthogonal relationship, the product of the two, ie, ωLI2, is the reactive power. Therefore, the reactive power Qm viewed from the motor side is expressed as the sum of the two reactive powers as shown in Expression 2.

[0015]

(Equation 2) Since the values of the reactive powers obtained by Expressions 1 and 2 are equal only by different viewpoints, the relationship of Expression 3 is established.

[0016]

[Equation 3] When Equation 3 is solved for a term proportional only to id, Equation 4 is obtained.

[0017]

(Equation 4) ψm is the magnetic flux created by the permanent magnet, and is uniquely determined for the electric motor. Therefore, if the voltage is adjusted so that the right side of Equation 4 approaches zero, Id = 0 control becomes possible. In addition, the above equation 3 can be modified as in the following equation 5.

[0018]

(Equation 5) Therefore, if the voltage is adjusted so that the right side of Equation 5 approaches zero, the reactive power proportional to id, that is, ωψmid, can be reduced to zero.

As described above, the d-axis current id which cannot be known by a device having no rotor position detector is obtained by calculation, and the voltage applied to the motor is adjusted so that id which does not contribute to torque generation is made zero. Control.

FIG. 3 is a control block diagram for explaining an embodiment of the present invention.
1, 2-phase / 3-phase coordinate conversion means 12 and 17, 3-phase PWM
It comprises an inverter 13, a lead phase control means 14, a current speed / position estimating means 15, a step-out detecting means 16, a motor model calculating means 18, a current detecting means 19, and a permanent magnet type synchronous motor 20.

The operation of the control device is as follows. Two-phase currents Iu and Iv of the permanent magnet synchronous motor 20 are detected by the current detecting means 19, and the two-phase / 3-phase coordinate converting means 17 converts the current values into the coordinate values. Current values Id, Iq
And the current value Im calculated by the motor model calculating means 18
Based on the differences Δid and Δiq from d and Imq, a step-out and unstable region of the motor are detected.

Here, if the d-axis current error Δid is within a predetermined range of a <Δid <b, it is determined that the operation is stable, and if it is outside the predetermined range, it is determined that the operation is unstable.

When .DELTA.id.ltoreq.a, control is performed to delay the phase, and when b.ltoreq..DELTA.id, control is performed to advance the phase.

Further, when correcting the current position θ of the rotor (not shown) of the permanent magnet type synchronous motor 20, the same judgment as in the above-described control is performed.

Although the present invention has been described based on the above-described embodiment, the present invention is not limited to this.

[0026]

As described above, according to the first aspect of the present invention, the control device of the present invention can detect the stability of the current operating condition of the electric motor only by the calculation. A highly efficient and reliable motor control device can be provided at low cost.

According to the second aspect of the present invention, the control device of the present invention corrects the phase after detecting step-out,
By correcting the Id current target value, stable operation of the motor is enabled, and a highly efficient and reliable motor control device can be provided at low cost.

According to the third aspect of the present invention, the control device of the present invention corrects the phase after detecting step-out,
By correcting the estimated current position θ, stable operation of the motor becomes possible, and a highly efficient and reliable motor control device can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a vector diagram for explaining a basic principle of vector control according to the present invention.

FIG. 2 is a vector diagram for explaining a basic principle of vector control according to the present invention.

FIG. 3 is a control block diagram of a permanent magnet type synchronous motor showing an embodiment of the present invention.

FIG. 4 is a control block diagram showing a control device of a conventional permanent magnet type synchronous motor.

[Explanation of symbols]

 12, 17 coordinate conversion means 15 speed / position estimation means 16 out-of-step detection means 18 motor model calculation means 19 current detection means 20 permanent magnet type synchronous motor

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshinori Nakayama 1 Otsukicho, Ashikaga-shi, Tochigi Sanyo Electric Air Conditioning Co., Ltd. F-term (reference) 5H560 BB04 BB12 DC12 EB01 TT08 XA02 XA12 XA13 XA15 5H576 BB02 BB06 DD02 DD07 EE01 EE11 GG04 HB01 JJ04 LL12 LL22 LL39 LL41 LL56 MM10

Claims (3)

[Claims] 1. A control device for a permanent magnet type synchronous motor, wherein a voltage applied to a winding of the permanent magnet type synchronous motor and its frequency are controlled by a power converter in approximately proportion. Means for detecting a current value of a phase, coordinate conversion means for separating the detected current value into a current component parallel to a voltage vector applied to the motor and a current component orthogonal to the voltage vector, and the detected current and coordinate conversion Means for detecting a step-out and unstable region of the motor from a difference from a current value calculated from a model of the means. 2. The motor according to claim 1, wherein the target current value is corrected based on the difference between the currents in which the step-out and the unstable region of the motor are detected to correct the phase of the output voltage. Control device. 3. The motor according to claim 1, wherein the position estimated by the rotor position estimating section of the motor is corrected based on the difference between the currents in which the step-out and the unstable region of the motor are detected. Control device.